Metal-metal interactions in dinuclear ruthenium complexes incorporating stepped-parallel bridging ligands: synthesis, stereochemistry and intervalence charge transfer

The synthesis and separation of the diastereoisomeric forms of the complexes [{Ru(bpy)(2)}(2) (mu-BL)](4+) based on the series of stepped-parallel bridging ligands 2,5-bis(2-pyridyl)pyrazine (2,5-dpp), dipyrido(2,3-a;2',3'-h)phenizine (dpop) and azobis(2-pyridine) (apy) are reported. Electrochemical and intervalence charge transfer (IVCT) studies on the complexes reveal a high degree of metal-metal interaction, consistent with a negligible solvent dependence of the IVCT parameters in each case. The results support a Class II-III classification for the systems.